Dodge & burn on 50% grey
Dodge & burn on 50% grey is the non-destructive way to sculpt light and shadow in Photoshop. You make a layer filled with neutral grey, set it to Soft Light or Overlay and paint with a soft black-and-white brush. The grey is invisible, only your light and dark work counts.
Make a new layer, fill it with 50% grey and choose blending mode Soft Light for subtle or Overlay for stronger. Paint with white to dodge (lighter) and black to burn (darker), at a low brush opacity for control. That lets you accentuate shape on skin, add depth to a landscape or make a product glow nicely. Tip: temporarily set the layer to Normal to check your grayscale sketch before building further.
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The presets on this site set these adjustments up for you as a starting point, which you then fine-tune to taste.